The invention relates to a method for monitoring utilization of an electrochemical energy storage device (a battery) in a motor vehicle, in which an electric drive is powered by the electrochemical energy storage device (electric current). In such a motor vehicle, the electrochemical energy storage device is discharged during continuing operation, when the electric drive is used. The electrochemical energy storage device can be charged at a charging station to which the vehicle is driven. The state of charge of the electrochemical energy storage device is important. State of charge refers to the level of the charge of the energy storage, wherein the state of charge is typically expressed as a percentage, with a state of charge of 0% referring to a completely discharged (to the minimum possible remaining charge) electrochemical energy storage device and the state of charge of 100% referring to the electrochemical energy storage device being charged to the maximum amount of charge. Typically, the percentage values are expressed proportional to the unit of charge (Coulomb).
An electrochemical energy storage device such as a lithium-ion battery usually suffers damage, when the state of charge is outside a predetermined range, i.e. when the state of charge is less then a specified minimum (during operation of the vehicle or of the electrical drive) or when the state of charge is greater than a specified maximum.
The normal operating mode of the motor vehicle is therefore a mode in which the state of charge of the electrochemical energy storage device remains in a predetermined range. Since this range is usually selected so as to provide a certain safety margin, the predetermined range may be left in exceptional cases.
This purpose it is known to allow the vehicle operator to provide an input (for example, the possibility of pressing a specific button, a particular key or by way of menu control), wherein the motor vehicle enters into a second operating mode in response to the input, wherein the battery is charged further.
A similar approach is also possible when a driver desires to reach a particularly high state of charge before staring to drive: In this case, the predetermined range is exceeded.
However, there is a risk that the operator abuses the special function and permanently damages the electrochemical energy storage.
DE 195 03 917 C2 discloses an electronic battery monitor with traction batteries for an electric vehicle wherein battery-related data are stored in a data store. The stored data include, among other things, information about the number of charge and discharge cycles, about deep discharges, about extreme values, etc. This is intended to provide tamper-proof information about the operating profile of the battery during its lifetime.
However, this does not include a situation where a driver may intentionally cause a deep discharge.